"I never thought that you would read this book," Yaffe writes in the letter, "or that it would be possible to fully live up to your greatness, but I gave it my all anyway."

As Yaffe tells Day 6 host Brent Bambury, Mitchell is very protective of her personal story.

"There was something about her that wanted to reveal things. And she's a born storyteller. She loves to tell stories," explains Yaffe. "But then she later regrets it, because then she feels she gave too much away."

Mitchell addresses that issue in her song, "Talk to Me," in which she sings:

"Oh I talk too loose

Again I talk too open and free

I pay a high price for my open talking

Like you do for your silent mystery."

Despite her success, Mitchell is vulnerable. And suspicious. That is, in part, why writing her biography was so daunting for Yaffe.

"She would reveal things to me and then regret it, and then do it again and regret it," says Yaffe.

Yaffe crafted Mitchell's biography over a 10-year period, during which he spent hours interviewing Mitchell. He also spoke with more than 60 of the people closest to her.

Joni Mitchell plays to a sold out crowd at General Motors Place in Vancouver in 1998. (Nick Procaylo/Canadian Press)

Influence and Leonard Cohen

"He recognized her greatness but she was also a beautiful woman that he wanted to get close to."- David Yaffe, referring to Leonard Cohen's attaction to Joni Mitchell

Leonard Cohen performing in Nov. 1966 on CBC. His debut album, Songs of Leonard Cohen, would be released the following year. (Michael Reichman/CBC Still Photo Collection)

That was how Yaffe learned that Cohen not only influenced one of Mitchell's biggest hits, "A Case of You," from the album Blue, but that Mitchell also influenced Cohen, including for his songs "Bird on a Wire" and "Joan of Arc."

Cohen and Mitchell had a short-lived romance in the 1960s, and much to his surprise, Yaffe found Cohen quite willing to talk with him for the Mitchell biography.

"It just happened, that he decided he wanted to meet with me. It was very spontaneous," says Yaffe.

"We went to this pizza place and he kept on saying: 'Isn't this place great? Isn't this place great?' And he called the waitress 'darlin'."

Cohen spoke very openly about Mitchell. He was drawn to her because she was "a great artist, and a great singer, and a great writer and guitar player."

"To him, these were discreet things," says Yaffe. "He recognized her greatness but she was also a beautiful woman that he wanted to get close to."

Stepping away from public life

But Yaffe says Mitchell has made many attempts over the years to step away from the limelight.

"She hated the music business so much, but she felt that she had such a responsibility to her gift — what I would call her genius."

Quitting the music industry was something Mitchell addressed in several songs, including "River":

"I'm going to make a lot of money

Then I'm going to quit this crazy scene

I wish I had a river

I could skate away on."

"But then she kept on going back in," says Yaffe. "It was cyclical that she would try to get out of it and think, 'oh, I'm just going to paint'. But then more songs would come."

When asked if Yaffe thinks she'll make another album, he says "that's highly unlikely." Both because of her health and her lack of interest in recording more music.

"It think that's it, probably."

Yaffe is a huge fan of Mitchell's. He says writing this book changed him. In his letter to Mitchell he thanks her for her music, her words and her influence.

"I was so fortunate that I had the opportunity to listen to you, to learn from you" he writes. "And to spread the word about this magnificent, defiant and totally original woman to whom I dedicated years of my life … You were worth it all."

Joni Mitchell's biographer reads a letter he wrote to the artist1:22

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